1,4-addition of stabilized carbanions
The ionic liquid [bmIm]OH is a catalyst and a reaction medium for Michael additions. Although the addition to α,β-unsaturated ketones gives the monoaddition products, this ionic liquid always drives the reaction of open-chain 1,3-dicarbonyl compounds with α,β-unsaturated esters and nitriles toward bis-addition.
B. C. Ranu, S. Banerjee, Org. Lett., 2005, 7, 3049-3052.
Triphenylphosphine and tributylphosphine are excellent catalysts for Michael additions of β-dicarbonyl compounds to electron-poor olefins, including sterically demanding partners.
C. Gimbert, M. Lumbierres, C. Marchi, M. Moreno-Mañas, R. M. Sebastián, A. Vallribera, Tetrahedron, 2005, 61, 8598-8605.
A practical and highly enantioselective Michael addition of malonates to enones to yield 1,5-ketoesters with good yields and excellent enantioselectivities is catalyzed by a simple and readily available bifunctional primary amine-thiourea derived from 1,2-diaminocyclohexane. The addition of weak acids and elevated temperature improved the efficiency of the reaction. This approach is applicable in multigram scale synthesis.
K. Dudziński, A. M. Pakulska, P. Kwiatkowski, Org. Lett., 2012, 14, 4222-4225.
A highly enantioselective Michael addition of malonates to α,β-unsaturated ketones in water is catalyzed by a primary-secondary diamine catalyst containing a long alkyl chain. This asymmetric Michael addition process allows the conversion of various α,β-unsaturated ketones.
Z. Mao, Y. Jia, W. Li, R. Wang, J. Org. Chem., 2010, 75, 7428-7430.
A chiral strontium complex promotes the catalytic asymmetric Michael addition reactions of malonates to enones at room temperature, to afford the desired adducts in high yields and excellent enantioselectivities. This method provides an efficient approach to building blocks possessing various functional groups and possible sites for further functionalization.
M. Agostinho, S. Kobayashi, J. Am. Chem. Soc., 2008, 130, 2430-2431.
A highly enantioselective and effective Michael addition of diethyl malonate to various chalcone derivatives has been achieved under mild phase-transfer conditions using a chiral quaternary ammonium bromide as a catalyst.
T. Ooi, D. Ohara, K. Fukumoto, K. Maruoka, Org. Lett., 2005, 7, 3195-3197.
Various bis-activated cyclopropenes undergo highly stereoselective ring-opening reactions to produce multisubstituted alkenyl halides in the presence of stoichiometric magnesium halides. Trapping of the magnesium enolate intermediates in situ allows the synthesis of highly functionalized compounds.
Y. Wang, H. W. Lam, J. Org. Chem., 2009, 74, 1353-1355.